Ments



(No ModELj O. E. SORIBNER.

NIGHT SIQNAL GIRGUIT FOE TELEPHONE EXOEANGEE, No; 293.196. Patented Feb. 5, 1884.

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CHARLES E. scninnnn, or CHICAGO, ILLINOIS, ASSIGNOR, BY nnsnn nssien- MENTS, TO THE wEsTnRNnLEcrnIc COMPANY, or SAME PLACE.

NlGHT==SlGNAL CiRCUlT FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 293,196, dated February 5, 1884.

- Application filed June 20, 1881. (No model.)

To coZZ whom it 'ntcty concern. I

Be it known that I, CHARLES E. SonInNEn, of Chicago, Illinois, have invented a certain new and useful Improvement inNight-Signal Circuits for Telephone-Exchanges, of which the following is a full, clear, concise, and exact description. Y

My inventibn consists in continuing the individual line or wire of any subscriber to the oiiices of many subscribers, and thereby providing for many subscribers a means of signaling the central station.

Figure 1 shows three subscribers stations,

1 2 3, connected with switches a b c at the central offiee in the usual manner. The 'nightcall apparatus consists of annunciator d and bell c,

placed in the circuit of battery f.

Fig. 2 shows another well-known way of connectlng stations 1, 2, and 3 with connecting plates or bolts a I) c at the central office;

The night-call is the same as shown in Fig. 1, and consists of annunciator dandbell c in circuit'of battcryf. The night-call apparatus is the same, whatever the system of connecting the subscriber with the central otfice, and is connected with any one of the switches the subscribers, as shown at a and a. I 1

In Fig. 1 the telephone-line r of station 1 is connected with many other stations, 2 3, 856., by the line h, and at the central office, by means of the plug and cord and line i, with the armature and shutter of annunciator (Z, through said annunciator and battery f to ground, as shown.

Any subscriber, by moving his switch so as to connect line h to ground, completes the circuit of battery f. As shown at station 3, Fig. 1, simply removing the telephone from the switch thus' completes the circuit of the battery from line it through connected lines of sta tions 2 and 3. Then the lines are open at the central office, as shown in Fig. 2, I provide keys 7t", one at each station, which, when dc pressed, connect the line it directly to ground. \Vhen the circuit is completed, the shutter of the annunciator is at once thrown down and the battery-circuit broken from the line i and directed through the bell e. The bell continues to ring when its circuit is thus closed to battery until the attendant is aroused.

If the battery were not instantaneously disconnected from line t'when line his connected to ground, the bell at station 1 in the circuit of line 9 would ring.

The listenin o )erators outfit is not shown in the drawings. It may be constructed,connected, and operated in the usual manner.

\Vhcn the telephone of any given station is hung 011 the switch-lever, the telephone-line of the station is disconnected from ground'and connected with the outer common line. Thus at station 1, Fig. 1, telephone-line g is shown .cut oil from the telephone and ground and connected with the outer line, It. At station 3, Fig. 1, the telephone is shown removed from the switch-lever. The telephone-line of station 3 is thus cut off from line It andconnected through the telephone to ground, as shown.

The switches or springjacks a b 0, Fig. 1, are of the form well known as the jackknife. plug is inserted the blade or circuit-changing piece is wedged away from the insulated contact-point of the switch. The telephone-line is thus cut off when a plug is inserted, as shown at switch a, Fig. 1. In Fig. 2 the telephone-lines terminate at the central oflice in connecting plates or bolts a, b, and c, and are not connected together or to ground at the central office. It is therefore unnecessary to provide jacklnii'fe-switches. Jackknifeswitches might, however, be used. The telephone-lines, as shown in Fig. 2, being normally open at the central oflice, it is unnecessary to provide 'ackknife-switches upon the switch-board, for they cannot be disconnected or out off unless they have been previously connected.

As before stated, the telephone-lines, as shown in Fig. 2, are normally open at the central office, and are not connected at the central office with a common line, with one another, or with anything else except the terminal plates or bolts a, b, and c.

Iclaii r The combination, in a telephone-exchange, with several individual telephone-lines con- They are so constructed that when a nected together by a common outer line, of a 1:0

branch circuit to ground at the central office at any snbscribers station through one or more containing a battery and annunciator, said of the individual lines and the common outer branch being adapted to be connected at the line. central office to any one of the te1eph0ne-1ines, CHARLES E. SCRIBNER.

5 and switching apparatus at each subscribers stationnvhereby the branch containing th e batvery and annunciator may be closed to ground *itnesses:

GEORGE I. BARTON, \VILLIAM. S. GRANGER. 

